It was always a thermodynamical and/or economical analysis and comparison in my carrier as “New Equipment” salesman
BUT, the story was changed as “Used Equipment” Salesman later;
Scrap cost comparison as starting point: Engines are usually heavier than gas turbines in terms of weight.
Value Of Equipment USD/kWe: similar
Constructional advantages: GTs are lighter in terms of weight against Gas/Diesel Engines. Dismantling and relocation are less costly for gas turbines.
Major overhaul cost: Usually gas turbines are more expensive.
Efficiency Degradation: higher in used gas turbines. Thermodynamics analysis might be different due to efficiency degradation in specific projects.
Old and traditional arguments from the past. True or not?
Same capacity of gas turbines and gas/diesel engines, as prime mover are subject to comparison. Balance of plant was not taken into consideration.